Dewaxing process



Patented Oct. 19, 1943 DEWAXIN G PROCESS James V. Montgomery, Fort Huach'uca, Aria, Luke B. Goodson, Phillips, Tex, and Robert W. Henry, Bartlesville, Okla", assignors to Phillips Petroleum Company, a corporation of Delaware Original application September 30, 1940, Serial No. 359,164. Divided and this application Angust 10, 1942, Serial No. 454,321

4 Claims.

This invention relates to mineral oil refining", and more particularly it relates to an improved dewaxing solvent. 1

This application is a division of our copending application, Serial No. 359,164, filed September 30, 1940, now Patent No. 2,303,570, dated December 1, 1942.

It is known to use he'terocyclic nitrogen base compounds such as pyridine, 'picolines, lutidines,

like for water-and thus improve the utility of the solvent.

Compounds suitable for use according to our invention include such as:

Terpenes of the type of limonene, methane, menthene, pinene,

Alkyl sulfides such as butyl, amyl sulfides,

Amines such as hexyl, heptyl amines,

Mercaptans such as .butyl, amyl, phenyl men collidines, etc., as extraction and dewaxing solcaptans, I vents, and it is known to use these nitrogen base Sulfur oils from gasoline caustic wash, solvents in conjunctionwith certain wax anti- Thiophene, and alkyl derivatives. solvents or solubility enhancing agents. In an The figure shows the relation of the miscibility application filed by James V. Montgomery and temperature lowering and the amount of added Robert W. Henry, Serial No. 358,342, filed Sepmaterial in the solvent. Referring to the figure, tember 25, 1940, now Patent No. 2,297,839, dated it is seen that a relatively small amount of lim- October 6, 1942, it was proposed to add to such onene (percent by volume) added to a picoline solvents as picolines, and those mentioned above, solvent materially lowers the miscibility tempercertain organic compounds having the property ature of the oil-solvent mixture, for example 5% of lowering the miscibility temperature with limonene in the picoline solvent lowers the miswaxy oil, and assisting with the removal of cibility temperature 10 F. Water from the solvent system. These organic In another example, not shown on the accomaddition agents in order to exhibit maximum panying graph, 5% limonene in a picoline solutility must possess boiling points below approxvent lowered the miscibility temperature of a imately 200 F., for example, it was suggested to waxy long residuum stock 9 F., from minus 14 add benzene, boiling point about 177 F., to the F. to minus 23 F. wet picoline solvent. Picolines and water form Of the compounds tested, limonene, diamyl la physical mixture boiling at a constant temperatide and amyl mercaptan were found to be the ture of approximately 0 F. most effective for lowering the miscibility tem- An object of this invention is to furnish an perature of t picoline-oil ixtu improved solvent for the dewaxing of lubricating oil stocks.

Another object of this invention is to furnish a dewaxing solvent which has an increased tolerance for dissolved water.

Still other objects and advantages will be apparent from a study of the disclosure that follows. We now propose to improve the utility of picolines and similar solvents by adding thereto certain organic compounds which lower the miscibility temperature of the solvent with waxy oils, increase the dewaxing selectivity of the solvent, and which have higher boiling points than those specified in the above mentioned application. These organic compounds are termed solubility enhancing agents. Our added solubility enhancing agents are in themselves selective and their presence in the solvent mixture not only lowers the miscibility temperature of the solvent and the oil to be dewaxed, but also increases the wax selectivity thereof. Since these compounds have higher boiling points they do not so readily assist in the removal of undesirable water from the solvent system, but they do increase the tolerance of picolines and the In carrying out our invention, we do not wish to be limited by any special type of dewaxing apparatus, since essentially any standard dewaxing equipment should be satisfactory. For dewaxing of the above mentioned long residuum stock at minus 20 F., the oil to be dewaxed is mixed with a picoline solvent containing 5% by volume (of the picoline solvent) or limonene, and the mixture warmed to insure complete and rapid solution of the oil in the solvent mixture. The mixture is then chilled to said dewaxing temperature of say, minus 20 F., followed by filtration in any suitable type of filter. Filtration is rapid since the wax crystals formed in this solvent mixture are distinct and sharp edged. The

slack wax may be washed with additional sol-- head as vapors and the oil exits from the lower portion thereof and is conducted to storage.

The solvent vapors from the above mentioned fractionator are condensed and the solvent mixture conducted to intermediate storage preparatory to reuse.

The used solvent mixture may contain a minute amount of moisture which had been ex-A tracted by the picoline solvent from the oil being.

dewaxed. Water tends to raise the miscibility temperature of a picoline and oil mixture, but to" offset this increase in miscibility temperature, a quantity of limonene had previously been added. Hence, the addition of this limonene had increased the toleration of the picoline solvent for water.

By occasional further additions of such materials as above mentioned, an example being limonene, picoline solvents or similar solvents may be used for extended periods of time without the necessity of having to be dehydrated or dried. Thus, the utility of picoline solvents is materially extended.

While we have described the use of limonene in a picoline dewaxing solvent, we do not wish to be limited in this manner since the materials or compounds heretofore mentioned function favorably in extending the utility of such solvents as the isomeric picolines, pyridine, lutidines, collidines, etc., or mixtures of the same such as occur in commercial pyridine.

What we claim is:

1. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and diamyl sulfide as a selective type solubility enhancing agent, which selective type agent increases the tolerance of the solvent mixture for water, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

2. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxlng solvent comprising a heterocyclic nitrogen base solvent, and diamyl sulfide as a solubility enhancing agent, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

3. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and diamyl sulfide as a solubility enhancing agent which increases the tolerance of the solvent mixture for water, chilling the oil-solvent mixture to precipitate the Wax, and removing the precipitated wax.

4. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and diamyl sulfide as a solubility enhancing agent, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

JAMES V. MONTGOMERY. LUKE B. GOODSON. ROBERT W. HENRY. 

